Pothead



Feb. 4, 1936.

F. c. MEYER ET AL.

POTHEAD Filed Dec. 16, 1952 2 Sheets-Sheet l INVENTORS ATTORN Y5.

Feb. 4, 1936-. F. c. MEY-ER El AL POTHEAD Filed Dec. 15, 1952 2 SheetS-She8t 2 INVENTORS ATTORNEYS.

Patented Feb. 4, 1936 UNITED STATES PATENT OFFICE POTHEAD Application December 16, 1932, Serial No. 647,520

1 Claim.

This invention relates to potheads for electric cables, and is particularly well adapted for use as a pothead construction for cables of the oil filled pressure type such for example as constituting the subject matter of Charles E. Benzliggt application Serial No. 553,714, filed July 29,

In such cable systems the insulated conductors of the cable are enclosed in a sheath or a pipe filled with oil under high pressure.

In the drawings accompanying this application two embodiments of the invention have been shown.

Fig. l is a part sectional elevational view of one embodiment of the invention;

Fig. 2 is a section on the line 2-2 of Fig. 1; and

Fig. 3 is a view similar to Fig. 1 of a modified form of the invention.

Referring to the drawings in detail and first of all to Figs. 1 and 2, I designates a metal sleeve or casing which is secured at its lower end by a wipe joint 2 to the outer sheath 3 of the cable designated 4. It might be noted at this point that the type of enclosure for the cable 4 does not constitute a part of the present invention. The type of enclosure shown comprises an inner lead sheath 5, outer sheath 3 and an intermediate sheath 6 of fabric such as canvas, for example, and as above noted this sheath is filled with oil under pressure, the introduction of this oil causing the inner lead sheath 5 to expand to the extent permitted by the intermediate sheath 6 so as to provide a reservoir for the oil about the exterior of the cable conductors. A steel or iron pipe such as shown in the Bennett copending application above referred to may be used with this pothead construction if desired.

The upper end of the casing or sleeve I is provided with a metal plate or cover I which is sealed to the end of the sleeve or casing i by bolts 8 and gasket 9.

The plate I is provided with thimbles ID screwed thereinto and each of these thimbles is equipped with a pressure tube II, these tubes at their lower end being screwed into the thimbles I0, while their upper ends are provided with a cap I2.

Each of the conductors of the cable is wound with metal tape l3 which is terminated at I4 for example, and to this tape is soldered metal braid I5 wound about the paper insulation of the cable. This braid or tinfoil I5 terminates at I6, for example. Slipped over each cable conductor is a metal cone I! which, as will be seen from the drawings, overlaps and contacts with the braid or tinfoil I5 at its lower end.

The conical member IT at its upper end is spaced slightly from the paper insulation of the paper conductor, and between this conical member I! and the insulation of the cable conductor is paper or varnished cambric I8 which is wound immediately about the paper insulation of the conductor and terminates at about the point designated I9.

Inasmuch as the pressure tube I I is considerably larger in diameter than the outside diameter of the conductor of the cable a barrier tube 20 is provided immediately about the insulated conductor between it and the pressure tube H. The lower end of each barrier tube terminates at about the upper end of the conical member l1, and about the lower end of each barrier tube is applied varnished cambric shown at 2| which is wound about the barrier tube in a conical form, a metal braid 22 being finally applied about this varnished cambric and contacting with the upper end of the cone H.

As above noted the upper end of each of the pressure tubes H is equipped with a cap I2 and the upper end of each conductor 23 of the cable is provided with a connector 24 which is soldered to the conductor or sweated thereto and projects through the end wall of the cap I2 where it is equipped with a nut 25 by which the connector is drawn into oil-tight contact with the cap I2.

As above pointed out the end of the cable sheath or pipe is in communication with the interior of the casing or sleeve I and as the pressure tube H is in communication with the interior of the casing or sleeve I the entire structure will be filled with oil under pressure, the degree of pressure of course depending upon the pressure carried within the cable pipe or sheath.

In Fig. 3 I designates a casing or sleeve similar to the casing or sleeve I of Fig. 1 which is attached to the cable pipe'or sheath by a wipe joint 2' and the upper end of this sleeve or casing I is capped by plate I bolted to the casing. As in the case of Fig. 1 the plate I is provided with thimbles I0 screwed thereinto, each thimble being equipped with pressure tube II screwed into the thimbles. Each pressure tube is provided at its upper end with a ring 26 to which is bolted a cap plate 21. Each conductor of the cable is provided with metal tape I 3' wound about the insulation of the cable, this metal tape terminating at M above the plate 1'. Above this tape I3, directly about the paper insulation of the conductor, varnished cambric or paper tape I8 is applied, this varnished cambric or paper tape terminating say at l9. About the lower end of this winding of varnished cambric or paper is applied a winding of copper tape 28 for shielding purposes, the lower end of this shield being soldered to the metal tape l3 of the conductor. About the exterior of the insulated conductor of the cable adjacent the upper end of the pressure tube II and between the pressure tube and the conductor insulation are barrier tubes 20'.

Adjacent the lower end of the pressure tube H is a shielding cone 29, a similar cone being provided adjacent the upper end of the pressure tube and designated 30.

As in the case of the structure shown in Figs. 1 and 2 the pressure tubes II' are under internal pressure depending upon the pressure carried within the sheath or pipe of the cable.

What is claimed is:-

A'pothead construction for electric cables of the solid stranded conductor pressure type comprising in combination a casing, the lower end of which is secured to the enclosing pipe orsheath of the cable, said casing communicating with the interior of said cable sheath or pipe, a sealed cap for said casing, a pressure tube of insulating material secured to said cap, an insulated cable conductor received by said tube, said tube being sealed at the top and communicating with the interior of said casing, a barrier tube within said pressure tube surrounding the insulated cable conductor, metal tape about the insulation of the conductor adjacent the lower part of said casing,

a shielding cone about said tape, insulation about the lower end of said barrier tube terminating adjacent the upper end of said shielding cone, and a metal shield about said insulation, the lower end of said shield being in contact with said cone.

FRED C. MEYER. GEORGE E. MOFF'I'I'I. 

